The invention relates generally to solids delivery systems for feeding solids into pressurized systems, more specifically to solids delivery systems utilizing bulk solids pumps, such as a rotary solids pump, to feed solids to a process or system operating at elevated pressure.
A wide variety of equipment has been used to pressurize, transport and feed particulate material such as, but not limited to, solid fuels, minerals, chemicals, fillers, polymers, and other dry materials handled in solid, particle form to chemical or thermal conversion processes or other systems, such as storage systems, operating at elevated pressures. Some non-limiting examples of such equipment include lock-hoppers, screw-type feeders, piston feeders, and various combinations thereof.
Bulk solids pumps can be an attractive means for pressurizing, transporting or feeding particulate materials into such processes or systems, either alone or in combination with other such pressurizing, transporting and feeding equipment. While bulk solids pumps, offer several benefits, there still exists a potential for process gas leakage back through such pumps during operation. This is the case for instance with a rotary solids pump in which the design allows process gas originating from downstream of the rotary solids pump to leak in an opposite direction of flow of solids. The leak may pose undesirable safety and operational concerns since process gas may be sufficiently combustible, reactive, corrosive, or toxic to create hazardous conditions if it mixes with gases or the atmospheres upstream of the pump, including ambient air. The process gas that is hot or cold beyond a desirable limit may also cause damage while entering regions of the pump and upstream system that are not designed for such conditions. Further, the process gas may contain species that could condense onto the solids in an upstream equipment, reacting with the solids or wetting the solids thus causing problems including with solids flow and plugging. Even in absence of the foregoing problems, the loss of process gas back through the rotary solids pump may be undesirable for cost reasons.
Further, such gas leakage unchecked could produce instabilities in the solids flow to and in the operation of a process or system, leading to other operational, equipment, and safety issues. A malfunction in a rotary type bulk solids pump also may lead to a large and uncontrolled leak of process gas that may be combustible, reactive, corrosive or toxic. The malfunction also has safety implications due to a sudden release of stored energy in the form of a pressurized gas.
Therefore, a need exists for an improved solids delivery system that may address one or more of the problems set forth above.